When it comes to developing a new application, you have many options for control: all-in-one controller boxes, integration-ready boards, and ASIC chips for complete customization. What factors should be taken into consideration when selecting a motion controller option?

A basic need of the machine design is to be able to go to a position, and knowing where that position is relative to the workpiece. In looking at achieving accuracy in the movement of a workpiece or the tooling, there are three areas of the machine design: the mechanical components, the command and control of the movement (control boards and servo loop), and the translation mechanism (linear motor or rotary motor and ball screw). This article is focused on one aspect of translation, specifically the force generated by linear electric motors.

There are three main direct drive linear motion systems on the market today. These three motor types have distinct advantages and disadvantages and, based on the application, one motor will be better suited than either of the other motors. This white paper will present the basic mechanism of operation of these three linear motors along with the advantages and disadvantages of each.

In order to operate a motor, you need a device or circuit that produces a speed and direction signal. In many cases, a CPU or FPGA device is used to create movement, because technically these devices can be programmed to generate pulses. However, no serious engineer should consider using these for important motion control applications, unless they are okay with a "good enough" mentality when it comes to their application's movement.

A pulse control LSI (motion control IC, ASIC) is a dedicated chip that is specialized for motion control. It is very easy to design programs when you use a convenient motion control-specific tool like a pulse control LSI. By choosing a pulse control LSI, you can easily write setting data and commands for both linear and S-curve acceleration/deceleration without overloading the CPU. When you consider CPU and engineering resource costs, ease of use, and speed of development, the end user benefits greatly from the specialized motion control option.

Linear motors have gained a name for themselves as being a high-precision and power-efficient alternative to conventional rotary-to-linear transmission systems. How is this possible? Well, let’s look at the Ball Screw, which also can be considered, in its own right, a high precision rotary-to-linear transmission system. The Ball Screw is typically only 90 percent efficient[1]. When we add the efficiency of the servo motor (range from 75 to 80 percent[2]) and losses that will be introduced by the coupling (and if using a gear box), it is possible that only 55 percent of the power we are supplying is going towards work. When we compare the typical linear motor, where the motor is driving the load linearly, we can quickly see why the linear motor has gained a name as being more power-efficient.

With the Linear Shaft Motor, you have the ability to drive two motors in parallel using only one encoder and one amplifier. All other systems require two drives, two controllers and two encoders, connected together. How is the Linear Shaft Motor able to overcome these issues?